The light sensitivity and unstable nature of 11-cis-retinoids makes them id
eal visual chromophores in nature. The synthesis of 11-cis-retinal analogue
s is of paramount importance in bioorganic studies of rhodopsin, the photor
eceptor of the visual transduction pathway, but the instability of 11-cis-r
etinoids complicates their synthesis and there is no general synthetic rout
e. Common strategies to the cis geometry have failed in the case of 11-cis-
retinoids, and most often low yields and complex isomeric mixtures are obta
ined. Herein we report an efficient, general, and mild preparation of 11-ci
s-retinoids by semi-hydrogenation of 11-yne-retinoid precursors with Cu/Ag-
activated zinc dust.